NEW ORLEANS -- Optical colonoscopy is superior to both air contrast
barium enema and computed tomographic colonography in detecting polypoid
lesions, results from a large multicenter trial suggest.

"All three tests are probably acceptable if detecting cancer
is the goal, [but] air contrast barium enema may not be justifiable for
use in patients in whom the only objective is to identify polypoid
lesions," Dr. Don C. Rockey said at the annual Digestive Disease
Week.

In a study funded by the National Cancer Institute, Dr. Rockey and
his associates compared the specificity and sensitivity of the three
imaging tests in 691 patients at 15 medical centers who had an
indication for a colon examination, including fecal occult blood,
hematochezia, iron deficiency anemia, or a family history of colon
cancer.

Study participants first underwent air contrast barium enema
(ACBE). A week or two later they underwent computed tomographic
colonography (CTC) and optical colonoscopy (OC) on the same day.
Preparations for all studies were standard, without stool tagging, and
the researchers were blinded to the findings on other tests.

Sensitivity was determined by matching of individual lesions for
location and size. "For example, a lesion 10 mm or greater in size
identified by colonoscopy would be considered a matching lesion if a
lesion 5 mm or greater in size was identified in the same or in an
adjacent segment on either imaging test," said Dr. Rockey, who
directs the liver center at Duke University Medical Center, Durham, N.C.

The researchers were "highly experienced in ACBE and
colonoscopy," he said. Experience with CT colonography varied, but
all inexperienced readers had identical training in the procedure before
the study began.

The mean age of study participants was 57 and about one-third were
female. Of the 691 patients, 63 had 76 lesions 10 mm or greater in size,
of which 55 were either adenomas or cancers; 116 had 154 lesions that
were 6-9 mm in size, of which 97 were adenomas or cancers.

The per-patient sensitivity for detecting lesions at least 1 cm in
size regardless of histology was 48% for ACBE, 59% for CTC, and 98% for
OC. Sensitivity was significantly greater for OC than for the other two
tests.

The sensitivity for detecting lesions 6-9 mm in size was 35% for
ACBE, 51% for CTC, and 99% for OC. Again, sensitivity was significantly
greater for OC than for either of the other two tests.

When only adenomas and cancers were considered in the analysis, the
sensitivity of ACBE and CTC increased slightly, but overall trends
remained the same. The sensitivity for detecting adenomatous and
cancerous lesions at least 1 cm in size was 55% for ACBE, 64% for CTC,
and 99% for OC. The sensitivity for detecting adenomatous and cancerous
lesions 6-9 mm in size was 31% for ACBE, 60% for CTC, and 100% for OC.
"It should be noted that differences between barium enema and CTC
were slightly more pronounced in the 6-to 9-mm lesion category,"
Dr. Rockey said.

Meanwhile, the specificity for detecting lesions at least 1 cm in
size regardless of histology was 90% for ACBE, 96% for CTC, and 100% for
OC. The specificity for detecting lesions 6-9 mm in size was 82% for
ACBE, 89% for CTC, and 100% for OC.

After undergoing all three procedures, patients were asked to rate
each test. "Patients felt there was no real difference in the
difficulty of the preparations, or with regard to respect or a loss of
dignity during any of the procedures," Dr. Rockey noted.
"However, subjects felt that ACBE was the most uncomfortable test
and that colonoscopy was the most comfortable. Additionally, patients
were most willing to repeat colonoscopy."

He pointed out that CTC is a "rapidly moving field" and
that more studies of its efficacy are underway.

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